The interplay of selective occupation and magnetic properties of high entropy spinel oxides

We investigate the interplay between the selective occupation (cationic site and valence preferences) and magnetic properties of three high entropy spinel oxides (HESOs). One of the samples ((Co,Cr,Fe,Mn,Ni) 3 O 4 ) is well known in the literature, while the other two HESOs ((Co,Fe,Mn) 3 O 4 , (Co,Fe,Mn,Ni) 3 O 4 ) are unstudied. XAS and RIXS of the transition metal L-edge, and ligand field theory (LFT) calculations were also used to determine the selective occupation. We found that nickel and chromium assume exclusively O h 2 + and O h 3 + sites, respectively. Iron undergoes a transition from O h 3 + to T d 3 + with increasing entropy. Manganese and cobalt adapt according to the remaining cations. The determined selective occupation can accurately predict the trend of the saturation magnetic moment μ s a t . The decrease in μ s a t correlates with the transition of iron cations. Gaining a more extensive understanding of how the selective occupation is directed, and what implications this has on the structural, electronic, and magnetic properties, will lead the way to tailoring HESOs to individual applications.